#include <reg52.h>
#define uint unsigned int
sbit led1 = P1^0;
void delay1s()
{
   uint i,j;
	 for(i=500;i>0;i--)
	   for(j=110;j>0;j--);
	

}
void main ()
{
	
	while(1)
	{
  led1 = 0;
	delay1s();
	led1 = 1;
	delay1s();
	}

}